Quest Diagnostics Health Trendsâ¿¢ analysis also finds marijuana is the most commonly abused drug in the United States, but medical marijuana users are not more likely to misuse other drugs

MADISON, N.J., April 8, 2013 /PRNewswire/ -- Individuals who use marijuana recreationally are more likely to misuse other drugs, including pain-controlling, but potentially addictive narcotics, sedatives and other prescription medications, than individuals who do not use marijuana, according to a new national study issued today by Quest Diagnostics (NYSE: DGX), the world's leading provider of diagnostic information services.

The study also found that while marijuana was the most frequently abused drug of patients tested, individuals who used prescribed marijuana (prescription cannabinoids) were not more likely to misuse other drugs than non-marijuana users.

The Quest Diagnostics Health Trends™ report, A Report on Marijuana and Prescription Drug Misuse in America, is believed to be one of the largest studies of the correlation between marijuana and prescription drug use in a nationally representative population based on objective laboratory data.

The report is now available at QuestDiagnostics.com/HealthTrends. The company will present additional findings from the report during the 2013 American Academy of Pain Medicine (AAPM) Annual Meeting, April 11-14, 2013, in Fort Lauderdale, Florida (booth 207).

"This study provides important evidence that people who use marijuana have greater risk of other forms of drug misuse. Future research is needed to determine the exact nature of this relationship and to inform substance prevention efforts," said Christian Thurstone, M.D., assistant professor, psychiatry, University of Colorado School of Medicine and medical director of Denver Health, an adolescent substance abuse program in Denver.

The new Quest Diagnostics Health Trends study is based on an analysis of 227,402 de-identified urine lab-test results of patients, age 10 years and older, of both genders in 49 states and the District of Columbia performed by the company's clinical laboratories in 2011 and 2012 in connection with the company's prescription drug monitoring services. These services aid clinicians in monitoring patients for appropriate use of up to 26 commonly abused prescription medications, such as opioids and sedatives, and illicit drugs, such as marijuana and cocaine.

The key findings for marijuana use:

Marijuana was the most frequently detected non-prescribed drug, found in more than one in four (26%) of patients with inconsistent test results. An inconsistent result is one that indicates a patient did not use medications as prescribed, such as by combining them with other prescription or illicit drugs. These findings confirm other research on the prevalence of marijuana use, including a March 2013 Quest Diagnostics Drug Testing Index™ report that found marijuana was the most frequently detected drug among the nation's workforce.

Nearly half (45%) of patients who used marijuana recreationally also used other non-prescribed drugs -- most commonly sedatives and narcotic pain killers – compared to approximately one third (36%) of non-marijuana users. These findings suggest recreational marijuana users are 1.3 times more likely than non-marijuana users to use or combine potentially dangerous and addictive prescription and illicit drugs without a legitimate prescription or a clinician's oversight.

Thirty-seven percent of medical marijuana users (those taking prescribed cannabinoids as pharmaceutical preparations) misused other drugs. Although this data shows a significant percentage of patients prescribed cannabinoids also misused other drugs, it does not indicate they were less responsible than other patient populations.

Recreational marijuana users were only slightly more likely than non-users not to use their prescription drugs. A patient may not take a prescribed drug due to financial constraints and diversion, including illegal drug sales.

"Our data raises the possibility that people who use marijuana recreationally are more likely to misuse their prescribed medications and other drugs. This is disturbing in light of the prevalence of marijuana use and the epidemic of drug addiction and death due to prescription medication abuse in the United States," said F. Leland McClure, Ph.D., director, pain management, mass spectrometry operations, Quest Diagnostics.

"We also found that patients taking prescription cannabinoids did not combine other drugs at a significantly higher rate than other patients," said Dr. McClure. "While additional research is needed to confirm the findings, patients using prescribed cannabinoids may do so largely for legitimate medical reasons and not to engage in the type of abusive drug behavior for which this patient population is sometimes accused."